I’ll just take this off of the unanswered list.
X from the manga is the equivalent of Calem in Pokémon X & Y, which is the male character (your rival if you play as female, you if you play as male).
Also, what Dreepy said is correct:
“Ik what they mean
No they are not. X from the manga and Ash from the anime fill largely the same roles, but are not the same character”
commented Jan 27 by ☆SleepyDreepy☆
Hope this helps!